"I expect a heatsink to always be cold"
The purpose of the heat sink is to transfer heat. The rate of heat transfer depends in a complicated way on (a) the temperature difference between heat sink and air, (b) the exposed surface area, and (c) the air speed.
The heat sink is at its most effective if it is at the same temperature as the CPU. This is because this gives the maximum temperature difference between heat sink and air. This is why heat sinks are often made of copper: copper conducts heat well.
Let us suppose that the CPU is producing heat $Q$ (Watts) and that the heat sink transfer heat at a rate linear with the temperature difference:
$$ Q = K_\text{eff} (T_\text{CPU} - T_\text{air})$$
where $K_\text{eff}$ is the effective heat transfer coefficient. Solving for the CPU temperature:
$$ T_\text{CPU} = T_\text{air} + Q / K_\text{eff}$$
So, the CPU temperature is lowest when $K_\text{eff}$ is highest and $K_\text{eff}$ is highest when the heat sink, due it to having high thermal conductivity, is at nearly the same temperature as the CPU.
"I expect a heatsink to always be cold"
The purpose of the heat sink is to transfer heat. The rate of heat transfer depends in a complicated way on (a) the temperature difference between heat sink and air, (b) the exposed surface area, and (c) the air speed.
The heat sink is at its most effective if it is at the same temperature as the CPU. This is because this gives the maximum temperature difference between heat sink and air. This is why heat sinks are often made of copper: copper conducts heat well.
Let us suppose that the CPU is producing heat $Q$ (Watts) and that the heat sink transfer heat at a rate linear with the temperature difference:
$$ Q = K_\text{eff} (T_\text{CPU} - T_\text{air})$$
where $K_\text{eff}$ is the effective heat transfer coefficient. Solving for the CPU temperature:
$$ T_\text{CPU} = T_\text{air} + Q / K_\text{eff}$$
So, the CPU temperature is lowest when $K_\text{eff}$ is highest and $K_\text{eff}$ is highest when the heat sink is at the same temperature as the CPU.
"I expect a heatsink to always be cold"
The purpose of the heat sink is to transfer heat. The rate of heat transfer depends in a complicated way on (a) the temperature difference between heat sink and air, (b) the exposed surface area, and (c) the air speed.
The heat sink is at its most effective if it is at the same temperature as the CPU. This is because this gives the maximum temperature difference between heat sink and air. This is why heat sinks are often made of copper: copper conducts heat well.
Let us suppose that the CPU is producing heat $Q$ (Watts) and that the heat sink transfer heat at a rate linear with the temperature difference:
$$ Q = K_\text{eff} (T_\text{CPU} - T_\text{air})$$
where $K_\text{eff}$ is the effective heat transfer coefficient. Solving for the CPU temperature:
$$ T_\text{CPU} = T_\text{air} + Q / K_\text{eff}$$
So, the CPU temperature is lowest when $K_\text{eff}$ is highest and $K_\text{eff}$ is highest when the heat sink, due it to having high thermal conductivity, is at nearly the same temperature as the CPU.
